| This thesis studies the design, molecular beam epitaxial (MBE) growth, device fabrication, and DC performance of a novel InAs-based high-velocity transistor (HVT). With the help of the unique design of InAs HVT, a cutoff frequency fT of as high as 1Thz and a power-delay product of less than 1fJ are expected. The challenges involved with the successful operation of an InAs HVT are: obtaining high purity InAs, obtaining high crystalline quality AlxIn1-xAs1-ySb y with aluminum mole fraction exceeding the limit of miscibility gap, surface passivation, selective etching between InAs and (In)Al(As)Sb, and the design of the emitter-base and base-collector junctions.; High purity InAs was grown on GaAs, GaSb, and InAs substrates under various growth conditions. The best Hall mobilities of bulk InAs grown by MBE in this work are as high as 31,000 cm2V/s at 300K, close to its bulk limit of 33,000 cm2V/s, and 420,000 cm2V/s at 77K, both of which are the best results reported so far. The calculated mobilities at various lattice temperatures, with impurity scattering, polar optical phonon scattering, and dislocation scattering taken into account, are in good agreement with the experimental results. It is further shown by this work that, to take full advantage of transport properties of InAs, InAs HVT should be grown on InAs substrate instead of GaAs or GaSb to eliminate the dislocations introduced by lattice mismatch.; Hydrogen-plasma assisted MBE growth was used to improve the purity of InAs, which was found to be very effective in passivating residual impurities, especially acceptors, in InAs. Furthermore, we found that the native oxide removal from InAs substrate by hydrogen-plasma produces a much flatter surface than thermal removal as indicated by reflective high-energy electron diffraction (RHEED).; By using digital alloy technique, high crystalline AlxIn 1-xAs1-ySby lattice-matched to InAs with x = 0.2--0.4, which lies within the miscibility gap of x = 0.2--0.8, was achieved. Clear Pendellosung fringes can be seen from the measured five-crystal high-resolution X-ray diffraction curves for digital alloy AlxIn 1-xAs1-ySby, indicating high quality of the epilayer and perfect interface between InAs and AlxIn 1-xAs1-ySby. A strong photoluminescence (PL) signal was observed from the digital alloy AlxIn1-x As1-ySby for x = 0.27, 0.31, and 0.37.; Two passivation methods, sulfurization passivation and depleted passivation ledge, were both found effective in reducing surface recombination current in InAs. (Abstract shortened by UMI.)... |
